Incendiary composition containing lithium and a gelled hydrocarbon carrier

ABSTRACT

An incendiary composition containing lithium in a liquid hydrocarbon carrier.

United States Patent [1 1 Durfee 1 INCENDIARY COMPOSITION CONTAINING LITHIUM AND A GELLED I'IYDROCARBON CARRIER [75] Inventor: Robert L. Durfee, Annandale,.Va.

[73] Assignee: The United States of America as represented by the Secretary of the Navy, Washington, DC.

[22] Filed:

Apr. 18, 1968 [211 App]. No.: 722,492

[52] US. Cl 149/20, 149/22, 149/87, 149/94 [51] Int. Cl C06b 15/00 [58] Field of Search 149/20, 22, 87, 94

[56] References Cited I UNITED STATES PATENTS 2,530,489 11/1950 Van Loenen 149/87 X Aug. 28, 1973 Primary Examiner-Stephen J. Lechert, Jr. Attorney-R. S. Sciascia and J. A. Cooke [57 ABSTRACT An incendiary composition containing lithium in a liquid hydrocarbon carrier. 1

5 Claims, No Drawings INCENDIARY COMPOSITION CONTAINING LITHIUM AND A GELLED HYDROCARBON CARRIER BACKGROUND OF THE INVENTION The invention generally relates to an incendiary composition and more particularly to an incendiary composition containing lithium in a liquid hydrocarbon carrier.

An incendiary agent is generally used to provide a heat source which further ignites a combustible material. The effectiveness of a particular incendiary agent is demonstrated by its ability to ignite quickly and easily in a variety of environments and to provide a large amount of heat to effect complete combustion of an ignitable material such as propellant, an explosive or another metal which may be aluminum, boron or magnesium. One of the more adverse conditions under which an incendiary agent may be desired to perform effectively is in an underwater mine or in a highly humid atmosphere. Another property of an effective incendiary agent is high thermal conductivity by which the heat may be transferred to the explosive with little loss.

, SUMMARY OF THE INVENTION Accordingly, one object of this invention is to provide a substantially self-igniting incendiary agent.

Another object of the invention is to provide an effectiveunderwater incendiary agent.

A further object of thisinvention is to provide an incendiary agent with high thermal conductivity.

Still another object is to provide an improved explosive.

Briefly in accordance with one embodiment of this invention, these and other objects are obtained by an incendiary composition containing lithium in a liquid hydrocarbon binder.

DESCRIPTION OF THE PREFERRED EMBODIMENT The metal compositions are prepared by first mixing a liquid hydrocarbon with a gel resin such as Dow 3487, a polystyrene derivative, sold by Dow Chemical Company, until the resin is completely dispersed. The resultant gel is allowed to stand until it becomes viscous at which time the metal powder is added in a closed mixer.

The incendiary composition broadly consists of three components: the primary metal, such as aluminum, magnesium, boron and mixtures thereof; the secondary metal, such as lithium and lithium hydride; and, a liquid hydrocarbon binder which may be gelled. The effec tiveness of a particular metal composition as an incendiary agent may be measured by observing the damage done to a target. The principle of the test is that the weight loss of the target is the result of pyrolysis of the wood and vaporization of the adsorbed water, both of which require definite amounts of heat per unit weight loss. The weight loss then is directly proportional to the amount of heat adsorbed so that the target serves as a crude calorimeter.

An actual test procedure which has been successfully followed is to burn identical quantities (15 grams) of agent on the base of triangular a target, which include two walls, in such a manner that the flames are allowed to contact the vertical walls. The target material is made from clear pine, 54 inch thick walls and 1% inch thick triangular base. A 1 inch thick strip joins the two walls and serve to retain the burning agent in the triangular section between the two walls. Strips, inch thick, are placed adjacent to the walls of the floor of the target in order to separate the agent from contact with the walls. By measuring the weight loss of the walls separately from that of the base, the damage mechanisms are separated into components of convective heat transfer by contact with the flames (wall weight loss), and conductive heat transfer from the condensed phase products (base weight loss). All edges and cracks exposed to the heat are coated with a refractory cement in order to inhibit burning. The target pieces are weighed before and after burning to determine the weight loss. Measurements are only given for the base weight loss rather than the wall or the total weight loss because the base weight loss data is generally less scattered and because it is felt that base damage would be a better measure of conductive heat transfer which is a desired property of an incendiary agent.

During the burning, metal ignition delay times are also measured by visually observing when the metals ignited after the slurry ignition.

The following are examples of compositions successfully tested:

EXAMPLE 1 To a slurry containing 50 per cent (by weight) gelled hexane (4 per cent Dow 3487 gellant), the following concentrations of aluminum and lithium were added and then tested as previously described.-

To a slurry described in Example 1, the following compositions of magnesium and lithium were added and then tested.

TABLE II Composition by Base Wt. Loss Metal Ignition Wt. Percent (g Time (min) Li Mg 25.0 25.0 56 1- 2 3.2 20.0 30.0 53 t 8 1.7 16.5 33.5 45 :4 2.6 12.5 37.5 44 i 5 2.9 7.0 43.0 37 t 3 4.0 5.0 45.0 42 1 3 3.7 0.0. 50.0 53 t 4 5.5

Lithium-magnesium alloy EXAMPLE 111 To a slurry described in Example 1, 25 per cent (by weight) of lithium and 25 per cent (by weight) of boron were added and the resultant mixture wastested yielding a base weight less of 462tlgm and a metal ignition time of 0.3 min.

EXAMPLE IV To a slurry described in Example I, the following compositions of lithium hydride, aluminum and boron were added and then tested.

TABLE III Composition by Base Wt. Loss Metal Ignition Wt. Percent (gm) Time (min) Lil-l A1 B 25 25 52:3 5.3 l2.5 37.0 0 41:4 5.3 25 0 25 47:2 5.1 25 58:15 5.4

EXAMPLE V To a slurry described in Example I, the following compositions of aluminum, magnesium and boron were added with 25 percent (by weight) of lithium and tested.

The slurry may be made from a variety of liquid hydrocarbons including hexane, heptane, isooctane, cumene (isopropyl benzene) and JP-4 (a mixed hydrocarbon jet fuel with specific gravity at 15.5C of about 0.764 and a vapor pressure at 38C of 134-160 mm Hg), but hexane exhibits the best incendiary properties such as high base weight loss and low metal ignition time. W4 is a jet fuel which containsa mixture of hydrocarbons as described in the Rocket Propellant Handbook written by Kit and Evered and published by The MacMillan Company, N. Y. in 1960. In addition, the hydrocarbon may be gelled with common gelling agents such as Dow 3487, a polystyrene derivative or nitrocellulose although a gelling agent is not required in the incendiary composition. However, it was observed that there was a slight but consistent increase in base weight loss with increasing gellant concentration so that the best performing incendiary compositions are those that included 4 per cent (by weight) of gelling agent. Accordingly, the preferred composition is that which contains 20 per cent lithium and 30 per cent magnesium in hexane gelled with 4 per cent gellant.

The incendiary compositions also exhibit good rheological properties which enable it to be dispensed from a variety of weapons such as, for example, from a flame thrower.

What is claimed as new and desired to be secured by Letters Patent of the United States is:

1. An incendiary composition comprising:

a metal powder selected from the group consisting of lithium and lithium hydride; and

a gelled liquid hydrocarbon containing constituent selected from the group consisting of hexane, heptane, isooctane, cumene and a mixed hydrocarbon jet fuel with specific gravity at 15.5C of about 0.764, and a vapor pressure at 38C of 134-160 mmHg.

2. An incendiary composition according to claim 1 which includes an additional metal selected from the group consisting of magnesium, aluminum, boron and mixtures thereof.

3. An incendiary composition according to claim 2 wherein the metal powder is lithium hydride and the additional metal is aluminum.

4. An incendiary composition according to claim 2 wherein the metal powder is lithium, the additional metal is magnesium and the gelled liquid hydrocarbon is gelled hexane.

5. An incendiary agent according to claim 4 which comprises:

20 per cent by weight of lithium;

30 per cent by weight of magnesium; and,

50 per cent by weight of gelled hexane, containing 4 percent gelling agent. 

2. An incendiary composition according to claim 1 which includes an additional metal selected from the group consisting of magnesium, aluminum, boron and mixtures thereof.
 3. An incendiary composition according to claim 2 wherein the metal powder is lithium hydride and the additional metal is aluminum.
 4. An incendiary composition according to claim 2 wherein the metal powder is lithium, the additional metal is magnesium and the gelled liquid hydrocarbon is gelled hexane.
 5. An incendiary agent according to claim 4 which comprises: 20 per cent by weight of lithium; 30 per cent by weight of magnesium; and, 50 per cent by weight of gelled hexane, containing 4 percent gelling agent. 